java - I just can't get a fragment to work -
i trying add simple fragment , doing wrong. create blank "mainactivity" in android studio, add fragment , try wire up:
mainactivity.java:
package com.fragtester.fragtester.fragtester; import android.support.v7.app.actionbaractivity; import android.os.bundle; import android.view.menu; import android.view.menuitem; public class mainactivity extends actionbaractivity { @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); // check activity using layout version // fragment_container framelayout if (findviewbyid(r.id.fragment_container) != null) { // however, if we're being restored previous state, // don't need , should return or else // end overlapping fragments. if (savedinstancestate != null) { return; } // create new fragment placed in activity layout blankfragment firstfragment = new blankfragment(); // in case activity started special instructions // intent, pass intent's extras fragment arguments firstfragment.setarguments(getintent().getextras()); // add fragment 'fragment_container' framelayout getsupportfragmentmanager().begintransaction() .add(r.id.fragment_container, firstfragment).commit(); } } @override public boolean oncreateoptionsmenu(menu menu) { // inflate menu; adds items action bar if present. getmenuinflater().inflate(r.menu.menu_main, menu); return true; } @override public boolean onoptionsitemselected(menuitem item) { // handle action bar item clicks here. action bar // automatically handle clicks on home/up button, long // specify parent activity in androidmanifest.xml. int id = item.getitemid(); //noinspection simplifiableifstatement if (id == r.id.action_settings) { return true; } return super.onoptionsitemselected(item); } } activity_main.xml
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingleft="@dimen/activity_horizontal_margin" android:paddingright="@dimen/activity_horizontal_margin" android:paddingtop="@dimen/activity_vertical_margin" android:paddingbottom="@dimen/activity_vertical_margin" tools:context=".mainactivity"> <framelayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/fragment_container" android:layout_width="match_parent" android:layout_height="match_parent" /> </relativelayout> blankfragment.java
package com.fragtester.fragtester.fragtester; import android.app.activity; import android.net.uri; import android.os.bundle; import android.app.fragment; import android.view.layoutinflater; import android.view.view; import android.view.viewgroup; /** * simple {@link fragment} subclass. * activities contain fragment must implement * {@link blankfragment.onfragmentinteractionlistener} interface * handle interaction events. * use {@link blankfragment#newinstance} factory method * create instance of fragment. */ public class blankfragment extends android.support.v4.app.fragment { // todo: rename parameter arguments, choose names match // fragment initialization parameters, e.g. arg_item_number private static final string arg_param1 = "param1"; private static final string arg_param2 = "param2"; // todo: rename , change types of parameters private string mparam1; private string mparam2; private onfragmentinteractionlistener mlistener; /** * use factory method create new instance of * fragment using provided parameters. * * @param param1 parameter 1. * @param param2 parameter 2. * @return new instance of fragment blankfragment. */ // todo: rename , change types , number of parameters public static blankfragment newinstance(string param1, string param2) { blankfragment fragment = new blankfragment(); bundle args = new bundle(); args.putstring(arg_param1, param1); args.putstring(arg_param2, param2); fragment.setarguments(args); return fragment; } public blankfragment() { // required empty public constructor } @override public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); if (getarguments() != null) { mparam1 = getarguments().getstring(arg_param1); mparam2 = getarguments().getstring(arg_param2); } } @override public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) { // inflate layout fragment return inflater.inflate(r.layout.fragment_blank, container, false); } // todo: rename method, update argument , hook method ui event public void onbuttonpressed(uri uri) { if (mlistener != null) { mlistener.onfragmentinteraction(uri); } } @override public void onattach(activity activity) { super.onattach(activity); try { mlistener = (onfragmentinteractionlistener) activity; } catch (classcastexception e) { throw new classcastexception(activity.tostring() + " must implement onfragmentinteractionlistener"); } } @override public void ondetach() { super.ondetach(); mlistener = null; } /** * interface must implemented activities contain * fragment allow interaction in fragment communicated * activity , potentially other fragments contained in * activity. * <p/> * see android training lesson <a href= * "http://developer.android.com/training/basics/fragments/communicating.html" * >communicating other fragments</a> more information. */ public interface onfragmentinteractionlistener { // todo: update argument type , name public void onfragmentinteraction(uri uri); } } fragment_blank.xml:
<framelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.fragtester.fragtester.fragtester.blankfragment"> <!-- todo: update blank fragment layout --> <textview android:layout_width="match_parent" android:layout_height="match_parent" android:text="@string/hello_blank_fragment" /> </framelayout> what doing wrong?!?!? have done bunch of different tutorials , cannot working me. please help! frustrated.
are encountering errors? because looking @ code, can see you've created default fragment , automatically added callback interface fragment, mainactivity class not implement. i'm sure if looked @ logcat, see error message along lines of "mainactivity must implement onfragmentinteractionlistener".
in future, learn check logcat , post stacktrace if have one, it'll make getting answer easier.
to fix this, should remove callback interface fragment, i'm sure won't needing @ point. this, remove following lines of code blankfragment:
private onfragmentinteractionlistener mlistener; // ... // todo: rename method, update argument , hook method ui event public void onbuttonpressed(uri uri) { if (mlistener != null) { mlistener.onfragmentinteraction(uri); } } @override public void onattach(activity activity) { super.onattach(activity); try { mlistener = (onfragmentinteractionlistener) activity; } catch (classcastexception e) { throw new classcastexception(activity.tostring() + " must implement onfragmentinteractionlistener"); } } @override public void ondetach() { super.ondetach(); mlistener = null; } /** * interface must implemented activities contain * fragment allow interaction in fragment communicated * activity , potentially other fragments contained in * activity. * <p/> * see android training lesson <a href= * "http://developer.android.com/training/basics/fragments/communicating.html" * >communicating other fragments</a> more information. */ public interface onfragmentinteractionlistener { // todo: update argument type , name public void onfragmentinteraction(uri uri); }
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